1. Technical Field
The present invention relates to a touch panel device that detects the position of a contact body on the coordinate system of a contact surface by transmitting surface acoustic wave sent from a sender element and receiving the surface acoustic wave on a receiver element.
2. Related Art
A touch panel device has a configuration wherein the position of a contact body is detected with a touch of the contact body to a contact surface. As such a touch panel device, a configuration wherein surface acoustic wave is transmitted from an interdigital transducer on the sender side and received on another interdigital transducer on the receiver side.
JP-UM-A-61-112444 (FIG. 4) is an example of related art.
A coordinate detector according to the example JP-UM-A-61-112444, which is used as a touch panel device, has two sender interdigital transducers for excitation purposes and two pairs of interdigital transducers for reception purposes.
The surface acoustic wave sent from one exciter interdigital transducer is received by one pair of receiver interdigital transducers on the opposite side. The surface acoustic wave sent from the other exciter interdigital transducer is received by the other pair of receiver interdigital transducers on the opposite side.
Since the above configuration requires two pairs of receiver interdigital transducers and each pair further includes a plurality of interdigital transducer elements, the wiring of the electric couplings becomes very complicated. In the case of reading the coordinates of a 20×20 matrix, for example, forty pieces of coupling wire are required for two pairs of receiver interdigital transducers alone, which causes a problem with wiring on the substrate periphery.